Noninvasive assessment of systolic left ventricular torsion by 2-dimensional speckle tracking imaging in the awake dog: repeatability, reproducibility, and comparison with tissue Doppler imaging variables

BACKGROUND: Left ventricular (LV) torsional deformation plays an important role in myocardial function. However, it has never been assessed in the awake dog, because magnetic resonance imaging and sonomicrometry have been the only methods available so far. HYPOTHESIS: Two dimensional speckle tracking echocardiography (STE), a new ultrasound imaging technique, provides a repeatable and reproducible noninvasive assessment of systolic LV wringing motion in the awake dog. ANIMALS: Six healthy dogs were used to determine the repeatability and reproducibility of STE variables (study 1). These variables also were prospectively assessed in a population of 35 healthy dogs (study 2). METHODS: Peak LV basal and apical systolic rotations were measured by STE from right parasternal short-axis views using automatic frame-to-frame tracking of gray-scale speckle patterns. Systolic LV torsion (LVtor, degrees ) was defined as apical rotation relative to the base. RESULTS: All within-day and between-day coefficients of variation were <20% (6.8-18.0%). Amplitude of apical systolic rotation was significantly higher (P < .001) than the basal value (5.4 +/- 3.2 degrees and -3.1 +/- 1.3 degrees , respectively). Global LVtor was significantly correlated with systolic longitudinal LV myocardial velocity gradient assessed by tissue Doppler (P < .05), but not with either systolic radial LV myocardial velocity gradient or the ratio of early mitral inflow velocity to early mitral annular velocity (Em/Ea). CONCLUSIONS AND CLINICAL IMPORTANCE: Speckle tracking echocardiography is a repeatable and reproducible method for assessing systolic LV torsional deformation. The combination of these new STE indices with tissue Doppler variables could provide a new approach for quantifying canine LV systolic function.     

Quantification, repeatability, and reproducibility of feline radial and longitudinal left ventricular velocities by tissue Doppler imaging

OBJECTIVE: To measure the radial and longitudinal velocities of several myocardial segments of the left ventricular wall by use of tissue Doppler imaging (TDI) in healthy cats and determine the repeatability and reproducibility of the technique. ANIMALS: 6 healthy cats. PROCEDURE: 72 TDI examinations were performed on 4 days by the same trained observer. Radial parameters included left endocardial and epicardial myocardial velocities. Longitudinal parameters included left basal, middle, and apical myocardial velocities. RESULTS: All velocity profiles had 1 positive systolic wave (S) and 2 negative diastolic waves (E and A). Myocardial velocities were higher in the endocardial than epicardial segments during the entire cardiac cycle (systolic wave S, 4.4 +/- 0.82 and 1.9 +/- 0.55; diastolic wave E, 9.7 +/- 1.70 and 2.2 +/- 0.74; and diastolic wave A, 5.1 +/- 1.56 and 1.4 +/- 0.76, respectively). Velocities were also higher in the basal than in the apical segments (systolic wave S, 4.7 +/- 0.76 and 0.2 +/- 0.11; diastolic wave E, 9.7 +/- 1.36 and 0.5 +/- 0.17; and diastolic wave A, 3.7 +/- 1.51 and 0.2 +/- 0.13, respectively). The lowest within-day and between-day coefficients of variation were observed in endocardial segments (8.2% and 6.5% for systolic wave S and diastolic wave E, respectively) and in the basal segment in protodiastole (5.5%). CONCLUSIONS AND CLINICAL RELEVANCE: Repeatability and reproducibility of TDI were adequate for measurement of longitudinal and radial left ventricular motion in healthy awake cats. Validation of TDI is a prerequisite before this new technique can be recommended for clinical use.     

Assessment of repeatability, reproducibility, and effect of anesthesia on determination of radial and longitudinal left ventricular velocities via tissue Doppler imaging in dogs

OBJECTIVE: To determine left ventricular free wall (LVFW) motions and assess their intra- and interday variability via tissue Doppler imaging (TDI) in healthy awake and anesthetized dogs. ANIMALS: 6 healthy adult Beagles. PROCEDURE: n the first part of the study, 72 TDI examinations (36 radial and 36 longitudinal) were performed by the same observer on 4 days during a 2-week period in all dogs. In the second part, 3 dogs were anesthetized with isoflurane and vecuronium. Two measurements of each TDI parameter were made on 2 consecutive cardiac cycles when ventilation was transiently stopped. The TDI parameters included maximal systolic, early, and late diastolic LVFW velocities. RESULTS: The LVFW velocities were significantly higher in the endocardial than in the epicardial layers and also significantly higher in the basal than in the mid-segments in systole, late diastole, and early diastole. The intraday coefficients of variation (CVs) for systole were 16.4% and 22%, and the interday CV values were 11.2% and 16.4% in the endocardial and epicardial layers, respectively. Isoflurane anesthesia significantly improved the intraday CV but induced a decrease in LVFW velocities, except late diastolic in endocardial layers and early diastolic in epicardial layers. CONCLUSIONS AND CLINICAL RELEVANCE: Left ventricular motion can be adequately quantified in dogs and can provide new noninvasive indices of myocardial function. General anesthesia improved repeatability of the procedure but cannot be recommended because it induces a decrease in myocardial velocities.     

Use of quantitative two-dimensional color tissue Doppler imaging for assessment of left ventricular radial and longitudinal myocardial velocities in dogs

OBJECTIVE: To determine left ventricular free wall (LVFW) radial and longitudinal myocardial contraction velocities in healthy dogs via quantitative 2-dimensional color tissue Doppler imaging (TDI). ANIMALS: 100 dogs. PROCEDURE: TDI was used by a single trained observer to measure radial and longitudinal myocardial movement in the LVFW. Radial myocardial velocities were recorded in segments in the endocardial and epicardial layers of the LVFW, and longitudinal velocities were recorded in segments at 3 levels (basal, middle, apical) of the LVFW. RESULTS: LVFW velocities were higher in the endocardial layers than in the epicardial layers. Left ventricular free wall velocities were higher in the basal segments than in the middle and apical segments. Radial myocardial velocity gradients, defined as the difference between endocardial and epicardial velocities, were (mean +/- SD) 2.5 +/- 0.8 cm/s, 3.8 +/- 1.5 cm/s, and 2.3 +/- 0.9 cm/s in systole, early diastole, and late diastole, respectively. Longitudinal myocardial velocity gradients, defined as the difference between basal and apical velocities, were 5.9 +/- 2.2 cm/s, 6.9 +/- 2.5 cm/s, and 4.9 +/- 1.7 cm/s in systole, early diastole, and late diastole, respectively. A breed effect was detected for several systolic and diastolic TDI variables. In all segments, systolic velocities were independent of fractional shortening. CONCLUSIONS AND CLINICAL RELEVANCE: LVFW myocardial velocities decreased from the endocardium to the epicardium and from base to apex, thus revealing intramyocardial radial and longitudinal velocity gradients. These indices could enhance conventional echocardiographic analysis of left ventricular function in dogs. Breed-specific reference intervals should be defined.     

Peak mean myocardial velocities and velocity gradients measured by color M-mode tissue Doppler imaging in healthy cats

We sought to assess the feasibility of recording the myocardial velocity gradients (MVGs) and mean myocardial velocities (MMVs) measured by color M-mode tissue Doppler imaging (TDI) in the free wall of unsedated normal cats (n = 18) with a 7.4-MHz probe equipped to record TDI images. The peak MVG and MMV values during the different phases of the cardiac cycle corresponded to certain color velocity patterns occurring in the left ventricular free wall (LVFW). Biphasic shifts were recorded in the tracings of both the MVG and MMV during early diastole (E1 and E2) as well as during the isovolumic relaxation (IVR) and isovolumic contraction (IVC) phases. Stepwise regression analysis showed that age was the only significant predictor for the peak MVG values during the 2nd phase of early diastole (E2) (r = -0.79, r2 = 0.63, and P < .001). The peak late diastolic MVG values were associated positively with age (r = 0.50, r2 = 0.25, and P < .05). The peak MMV values showed a negative association with age during E2 (r = -0.71, r2 = 0.50, and P < .001) as well as during early systole (Se) (r = -0.55, r2 = 0.30, and P < .05) and late systole (SI) (r = -0.62, r2 = 0.39, and P < .01). A positive association was found between age and the peak MMV values during late diastole (r = 0.54, r2 =- 0.29, and P < .05). The MVG values showed cyclic variations consistent with wall thickness changes. The accuracy of velocity determination and the spatial resolution of the system used were validated with a phantom. To our knowledge, this study is the 1st report of the application of this technique to the myocardium of cats,providing insights into the physiology of myocardial motion. It provides reference ranges of the peak MVG and MMV values for future studies of feline myocardial diseases.     

Reference range values of regional left ventricular myocardial velocities and time intervals assessed by tissue Doppler imaging in young nonsedated Maine Coon cats

OBJECTIVE: To describe and analyze the left ventricular free wall (LVFW) radial and longitudinal motions in a population of healthy Maine Coon cats by use of quantitative 2-dimensional color tissue Doppler imaging (TDI). ANIMALS: 23 healthy young Maine Coon cats (mean +/- SD: age, 2.1 +/- 0.9 years; weight, 5.0 +/- 1.0 kg). PROCEDURE: TDI was performed by the same trained observer (VC) on all cats. Radial LVFW velocities were recorded in endocardial and epicardial LVFW segments, and longitudinal velocities were recorded in the mitral annulus and in basal and apical LVFW segments. Isovolumic contraction and relaxation times were calculated in each myocardial segment, and the coefficients of variation (CVs; %) were determined for each TDI parameter. RESULTS: LVFW velocities were significantly higher in the endocardial layers than in the epicardial layers and also significantly higher in the basal than in the apical segments. Annular velocities were significantly higher than basal myocardial velocities in systole and early diastole. Coefficient of variation values were lower for radial velocities, particularly in systole, and were also lower for time intervals (16% to 22%) than for myocardial velocities (19% to 62%). CONCLUSIONS AND CLINICAL RELEVANCE: Because Maine Coon cats are predisposed to an inherited hypertrophic cardiomyopathy, which is a common cause of death in this breed, TDI could provide a useful tool for early detection of the disease. Tissue Doppler imaging indices may complete the conventional analysis of the left ventricular function in Maine Coon cats. However, the usefulness of TDI indices in the early detection of myocardial dysfunction needs to be clarified.     

Assessment of regional systolic and diastolic myocardial function using tissue Doppler and strain imaging in dogs with dilated cardiomyopathy

BACKGROUND: Tissue Doppler Imaging (TDI) or strain (St) imaging could provide sensitive indices for early detection and treatment follow-up of canine dilated cardiomyopathy (DCM). Analysis of TDI and St features in dogs with overt DCM is a prerequisite before using these new criteria in prospective screenings of predisposed families or in clinical trials. HYPOTHESIS: Radial and longitudinal right and left myocardial motion, assessed by TDI and St variables, is altered in dogs with DCM. ANIMALS: Case records for 26 dogs; 14 with DCM and 12 healthy controls of comparable age and weight were reviewed. METHODS: A retrospective analysis was conducted of conventional echocardiography, 2-dimensional color TDI, and St imaging data. RESULTS: The DCM group was characterized by decreases in radial and longitudinal systolic velocity gradients of the left ventricular free wall (LVFW), radial and longitudinal absolute values of peak systolic St of the LVFW, and longitudinal systolic right ventricular (RV) velocities (all P < .001 versus control) associated with longitudinal postsystolic contraction waves in 7/14 dogs. Early diastolic LVFW velocities also were decreased for longitudinal (P < .01) and radial (P < .05) motions. All radial LVFW, longitudinal basal LVFW, and RV systolic velocities were negatively correlated with heart rate (P < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: LV contractility along both the short and long axes is impaired in dogs with spontaneous DCM, as is systolic RV and diastolic LVFW function. These myocardial alterations are associated with an inverse force-frequency relationship. Studies now are needed to determine the comparative sensitivity of TDI and St variables for the early detection of canine DCM.     

Quantitative assessment of velocities of the annulus of the left atrioventricular valve and left ventricular free wall in healthy cats by use of two-dimensional color tissue Doppler imaging

OBJECTIVE: To analyze velocities of the annulus of the left atrioventricular valve and left ventricular free wall (LVFW) in a large population of healthy cats by use of 2-dimensional color tissue Doppler imaging (TDI). ANIMALS: 100 healthy cats (0.3 to 12.0 years old; weighing 1.0 to 8.0 kg) of 6 breeds. PROCEDURE: Radial myocardial velocities were recorded in an endocardial and epicardial segment, and longitudinal velocities were recorded in 2 LVFW segments (basal and apical) and in the annulus of the left atrioventricular valve. RESULTS: LVFW velocities were significantly higher in the endocardial than epicardial layers and significantly higher in the basal than apical segments. For systole, early diastole, and late diastole, mean +/- SD radial myocardial velocity gradient (MVG), which was defined as the difference between endocardial and epicardial velocities, was 2.2 +/- 0.7, 3.3 +/- 1.3, and 1.8 +/- 0.7 cm/s, respectively, and longitudinal MVG, which was defined as the difference between basal and apical velocities, was 2.7 +/- 0.8, 3.1 +/- 1.4, and 2.1 +/- 0.9 cm/s, respectively. A breed effect was documented for several TDI variables; therefore, reference intervals for the TDI variables were determined for the 2 predominant breeds represented (Maine Coon and domestic shorthair cats). CONCLUSIONS AND CLINICAL RELEVANCE: LVFW velocities in healthy cats decrease from the endocardium to the epicardium and from the base to apex, thus defining radial and longitudinal MVG. These indices could complement conventional analysis of left ventricular function and contribute to the early accurate detection of cardiomyopathy in cats.     

Assessment of left ventricular function using pulsed tissue Doppler imaging in healthy dogs and dogs with spontaneous mitral regurgitation

Pulsed tissue Doppler imaging (pulsed TDI) has been demonstrated to be useful for the estimation of left ventricular (LV) systolic and diastolic functions in various human cardiac diseases. The objectives of this study were to investigate the relationship between pulsed TDI and LV function by using cardiac catheterization in healthy dogs and to evaluate the clinical usefulness of pulsed TDI in dogs with spontaneous mitral regurgitation (MR). The peak early diastolic velocity (E'), peak atrial systolic velocity (A'), and peak systolic velocity (S') were detectable in the velocity profiles of the mitral annulus in all the dogs. In the healthy dogs, S' and E' were correlated with LV peak +dP/dt and -dP/dt, respectively. E' was lower in dogs with MR than in dogs without cardiac diseases. E/E' in the MR dogs with decompensated heart failure was significantly increased in comparison with those with compensated heart failure. The sensitivity and specificity of the E/E' cutoff value of 13.0 for identifying decompensated heart failure were 80% and 83%, respectively. In addition, E/E' was significantly correlated with the ratio of left atrial to aortic diameter. These findings suggest that canine pulsed TDI can be applied clinically for estimation of cardiac function and detection of cardiac decompensation and left atrial volume overload in dogs with MR.     

Pulsed tissue Doppler imaging of the left ventricular septal mitral annulus in healthy dogs

This study evaluated pulsed TDI variables including the isovolumic time interval and duration of the major wave in a population of large healthy dogs. Longitudinal myocardial motion at the septal mitral annulus was evaluated with pulsed TDI in 45 healthy adult dogs. Maximal myocardial velocities, isovolumic time intervals, and duration of the myocardial waves were measured. The correlation between time intervals and velocity variables was also investigated. The mean maximal systolic velocity was 6.92 ± 1.78 cm/sec, the mean early diastolic velocity (Em) was 6.58 ± 1.81 cm/sec, the mean late diastolic velocity (Am) was 5.10 ± 2.00 cm/sec, the mean isovolumic contraction time (IVCT) was 53.61 ± 95.13 msec, and the mean isovolumic relaxation time (IVRT) was 26.74 ± 57.24 msec. The early diastolic mitral inflow velocity (E)/Em ratio was 10.94 ± 3.27 while the Em/Am ratio was 1.40 ± 0.40. There was a negative correlation between Am duration and Am amplitude, and a positive correlation between the IVRT and Em/Am ratio (p < 0.05). The normal LV parameter using pulsed TDI method could be used as the reference range for identifying myocardial dysfunction in dogs.     

Evaluation of tricuspid annular plane systolic excursion measured by two-dimensional echocardiography in healthy dogs: repeatability,reference intervals,and comparison with M-mode assessment

Introduction

We sought to determine the feasibility, measurement variability, and within-day repeatability of tricuspid annular plane systolic excursion (TAPSE) measured by two-dimensional echocardiography (2D TAPSE), generate reference intervals for 2D TAPSE, assess agreement and correlation between 2D TAPSE and the conventional TAPSE measured by M-mode echocardiography (MM TAPSE), and to assess the ability of 2D TAPSE to track a drug-induced decrease in right ventricular (RV) function compared with MM TAPSE.

Diagnostic value of echo-Doppler and tissue Doppler imaging in dogs with pulmonary arterial hypertension

BACKGROUND: Diagnosis of pulmonary arterial hypertension (PAH) relies on Doppler measurement of pulmonic and tricuspid regurgitation (TR). However, these are not always detectable. HYPOTHESIS: Tissue Doppler imaging (TDI), a novel noninvasive ultrasound technique, provides indirect but sensitive and specific assessment of elevated systolic pulmonary artery pressure (SPAP) in dogs. ANIMALS: One hundred and five dogs with TR. METHODS: Prospective observational study. Dogs were categorized as presenting normal (group 1, n = 45), mildly increased (group 2, n = 19), or moderately to severely increased (group 3, n = 41) SPAP, based on TR peak velocities (< 2.5, 2.5-3.0, and > 3.0 m/s, respectively). Ten quantitative echo-Doppler- and TDI-derived variables were assessed, including the main pulmonary arterial diameter to aortic diameter ratio, pulmonary flow acceleration time, and acceleration-to-ejection time ratio, the Tei index of right ventricular function, and 6 longitudinal basal right ventricular TDI variables. RESULTS: A significant correlation was observed between SPAP and each of the 10 tested variables (P < .05). Conventional echo-Doppler variables were less discriminating than the TDI for predicting increased SPAP. The combined systolic and diastolic right TDI index had the highest sensitivity and specificity (89% and 93% respectively, for a cutoff of 11.8 cm/s) and could discriminate between dogs in group 1 from dogs in group 2. CONCLUSIONS AND CLINICAL IMPORTANCE: TDI provided effective predictors of systolic PAH and demonstrated that both alterations in right-sided systolic and diastolic myocardial function can occur with mild increases in SPAP.     

Demonstration of regional differences in equine ventricular myocardial velocity in normal 2-year-old Thoroughbreds with Doppler tissue imaging

REASONS FOR PERFORMING STUDY: Doppler tissue imaging (DTI) is a novel noninvasive method by which myocardial velocity can be assessed directly and it allows regional, rather than global, cardiac function to be evaluated. HYPOTHESIS: That regional differences in myocardial velocities exist within the equine ventricle. OBJECTIVES: To develop a repeatable examination technique for DTI in horses, describe DTI findings in various regions of the normal equine ventricle, compare colour (CDTI) and spectral (SDTI) techniques of DTI, and document regional differences in myocardial velocity. METHODS: Five regions of the ventricles (right ventricular wall, interventricular septum and left, right and caudal regions of the left ventricle) were evaluated using SDTI and CDTI in 20 clinically normal Thoroughbreds age 2 years. Individual repeatability of the method was determined by examination of one 6-year-old Thoroughbred on 6 occasions. RESULTS: Three major movements were observed in the ventricular walls in systole, early diastole and late diastole. The interventricular septum had a complex pattern of movement. The left region of the left ventricle and interventricular septum had the most rapid movement. The individual repeatability of CDTI was poor, while in systole and early diastole, but not late diastole, SDTI produced repeatable estimates of maximal myocardial velocity. The different velocity estimates obtained with SDTI and CDTI are not interchangeable. Regional differences in the peak mean and maximal myocardial velocities were found in systole and early diastole (P<0.05), but were not identified in late diastole. CONCLUSIONS: The SDTI modality appears to produce the most repeatable data. There are regional differences in myocardial velocity within the equine ventricles for systole and early diastole. POTENTIAL RELEVANCE: DTI shows potential as a tool for studying regional myocardial movement both in clinical cases suspected of having myocardial dysfunction and in a research setting. In particular, SDTI offers potential as a direct and noninvasive means to study early diastolic function of the equine ventricles.     

The repeatability,reproducibility, and influencing factors of intrarenal Doppler ultrasonography in dogs without heart disease

Renal impairment is concurrent with adverse outcomes such as heart disease in humans and dogs. Intrarenal Doppler ultrasonography (IRD) is used to assess intrarenal hemodynamics, and resistance index (RI) and venous impedance index (VII) are used to evaluate intrarenal hemodynamics in humans with heart failure. However, only a few studies have assessed the efficacy of IRD, especially VII, in dogs, and the methods differ between studies. Additionally, repeatability, reproducibility, and factors influencing IRD values have not been validated in dogs. This prospective, analytical study aimed to assess repeatability and reproducibility of IRD, and to clarify influencing factors of IRD in dogs without heart disease. We enrolled 78 dogs without heart disease. The RI and VII were highly reproducible, and the reference intervals for VII were 0.13–0.37. Differences in transducer (sector and convex) and posture (right lateral and supine decubitus position) had no effect on the IRD values. In contrast, RI and VII were higher in the renal vessels than in interlobar vessels. Age affected RI values (r = 0.39, P < 0.001), but there was no correlation between age, body weight, and VII. In conclusion, IRD is a repeatable and reproducible method to assess intrarenal hemodynamics in dogs. The findings also suggest that age should be considered while interpreting RI.     

Longitudinal left ventricular myocardial dysfunction assessed by 2D colour tissue Doppler imaging in a dog with systemic hypertension and severe arteriosclerosis

A 12-year-old sexually intact male Vendee Griffon Basset was presented for acute pulmonary oedema. Severe systemic systolic arterial hypertension (SAH) was diagnosed (290 mmHg). Despite blood and abdominal ultrasound tests, the underlying cause of the systemic hypertension could not be determined, and primary SAH was therefore suspected. Conventional echocardiography showed eccentric left ventricular hypertrophy with normal fractional shortening. Despite this apparent normal systolic function, 2D colour tissue Doppler imaging (TDI) identified a marked longitudinal systolic left ventricular myocardial alteration, whereas radial function was still preserved. Three months later, the dog underwent euthanasia because of an acute episode of distal aortic thromboembolism. Necropsy revealed severe aortic and iliac arteriosclerosis. SAH related to arteriosclerosis is a common finding in humans, but has not been previously described in dogs. Moreover, its consequence on longitudinal myocardial function using TDI has never been documented before in this species.     

Assessment of left ventricular function by two-dimensional speckle-tracking echocardiography in small breed dogs with hyperadrenocorticism

Background

Hyperadrenocorticism (HAC) is associated with an increased prevalence of hypertension. This study investigated the left ventricular function using two-dimensional speckle-tracking echocardiography (2D-STE) in small breed dogs affected with spontaneous HAC.Age-matched healthy controls (n = 9), dogs with pituitary-dependent hyperadrenocorticism (PDH, n = 10), and dogs with adrenal-dependent hyperadrenocorticism (ADH, n = 9) were included in this study. Conventional echocardiography, global longitudinal and circumferential strain, and strain rate were assessed.

Results

On group-wise comparison, left ventricular free wall (LVFWd) and interventricular septal thickness in diastole (IVSd) were thickest in the ADH group, followed by the PDH and controls (P = 0.014 and P = 0.001, respectively). Neither LVFWd nor IVSd was correlated with systemic blood pressure (P = 0.238 and P = 0.113, respectively). The values of all variables derived from the global strain and strain rate in longitudinal and circumferential directions followed the same pattern: highest in the controls, followed by PDH and then ADH (all P < 0.05, respectively). On multiple regression analyses, global longitudinal strain, global longitudinal strain rate in systole and early diastole, and global circumferential strain all decreased linearly with increased IVSd (all P < 0.05).

Conclusions

Left ventricular hypertrophy (LVH) was more prevalent in the HAC group compared to the control group. Association between hypertension and development of LVH was not identified. Decreased global longitudinal and circumferential strains were associated with increased IVSd. 2D-STE revealed significant decreases in systolic functions that were undetected using conventional echocardiography in the ADH and PDH groups.     

Assessment of global and regional left ventricular volume and shape by real-time 3-dimensional echocardiography in dogs with myxomatous mitral valve disease

Background: Left ventricular (LV) remodeling occurs in response to chronic volume overload. Real‐time 3‐dimensional (RT3D) echocardiography offers new modalities for LV assessment. Objective: To investigate LV changes in shape and volume in response to different severities of naturally acquired myxomatous mitral valve disease (MMVD) in dogs by RT3D echocardiography. Animals: Sixty‐five client‐owned dogs. Methods: Prospectively recruited dogs were classified by standard echocardiography into healthy, mild, moderate, and severe MMVD groups. Endocardial border tracking of LV RT3D dataset was performed, from which global and regional (automatically acquired basal, mid, and apical segments based on LV long‐axis length) end‐diastolic (EDV) and end‐systolic volumes (ESV), LV long‐axis length, and sphericity index were obtained. Results: Global and regional EDV and ESV (indexed to body weight) were most prominently increased in dogs with severe MMVD. All 3 regional LV segments contributed to increased global EDV and ESV with increasing MMVD severity, but mid‐EDV contributed the most to the global EDV increase. Furthermore, LV long‐axis length and LV sphericity index increased with increasing MMVD severity. Basal and apical EDV segments displayed the strongest association with sphericity index (P < .0001). Conclusions and Clinical Importance: The most prominent LV volume expansion was found in dogs with severe MMVD. Increased EDV, primarily in the mid‐segment, leads to rounding of LV apical and basal segments in response to increasing MMVD severity. Assessment of LV volume and shape potentially could allow early detection of dogs at risk for rapid progression into congestive heart failure.     

Quantification of left ventricular diastolic wall motion by Doppler tissue imaging in healthy cats and cats with cardiomyopathy

OBJECTIVE: To assess Doppler tissue imaging (DTI) for evaluating left ventricular diastolic wall motion in healthy cats and cats with cardiomyopathy. ANIMALS: 20 healthy cats, 9 cats with hypertrophic cardiomyopathy (HCM), and 9 cats with unclassified cardiomyopathy (UCM). PROCEDURE: A pulsed wave DTI sample gate was positioned at a subendocardial region of the left ventricular free wall in the short axis view and at the lateral mitral annulus in the apical 4-chamber view. Indices of diastolic wall motion were measured, including peak diastolic velocity (PDV), mean rate of acceleration and deceleration of the maximal diastolic waveform (MDWaccel and MDWdecel, respectively), and isovolumetric relaxation time (IVRT). RESULTS: The PDV of cats with HCM and 6 of 9 cats with UCM was significantly decreased, compared with that of healthy cats. In the 3 cats with UCM that had a PDV that was not different from healthy cats, MDWaccel and MDWdecel were greater, and IVRT was shorter than those of healthy cats. The IVRT in cats with HCM was longer than that of other cats. CONCLUSIONS AND CLINICAL RELEVANCE: Indices of diastolic function in cats with HCM, and in many cats with UCM, differed from those of healthy cats and were similar to those reported in humans with HCM and restrictive cardiomyopathy, respectively. However, the hemodynamic abnormality was not the same for all cats with UCM; some cats with an enlarged left atrium and a normal left ventricle (ie, UCM) had abnormal left ventricular wall motion consistent with restrictive cardiomyopathy while others did not.     

Comparison of the myocardial performance index derived by use of pulsed Doppler echocardiography and tissue Doppler imaging in dogs with volume overload

OBJECTIVE: To investigate the relationship between the myocardial performance index (MPI) determined by use of pulsed Doppler (PD) echocardiography and tissue Doppler imaging (TDI) in the response to volume overload-related changes in left ventricle (LV) performance. ANIMALS: 7 male Beagles. PROCEDURES: Dogs were anesthetized and intubated. A 6-F fluid-filled catheter was placed in the LV to measure LV peak systolic (LVPs) and LV end-diastolic (LVED) pressures. Preload was increased by IV infusion of lactated Ringer's solution (rate of 200 mL/kg/h for 60 minutes) into a cephalic vein. Transmitral flow velocities and aortic outflow were measured, and TDI velocities were obtained from the 4-chamber view. RESULTS: Acute volume overload induced a significant increase in heart rate, LVPs pressure, and LVED pressure, compared with baseline values. A significant decrease in the PD-MPI and TDI-MPI values and a significant correlation (r = 0.70) between PD-MPI and TDI-MPI were detected. The PD-derived A-wave velocity, ejection time, and isovolumic relaxation time (IRT) and the TDI-derived IRT, MPI, and ratio of the velocity of the E wave to the velocity of the ventricular portion of the E wave during early diastole had equal ability to predict LVED pressure (r(2) = 0.63). CONCLUSIONS AND CLINICAL RELEVANCE: The TDI-MPI was closely correlated with LV filling pressure and may be helpful in evaluating global cardiac function in dogs.